Where is ADCREF voltage set?

[Haddock]

I use ADC 12 bit in STM32L03 and cannot find where CubeIDE defines which reference voltage the ADC should have. ADC_Init() is auto-generated. Is it the default used and what voltage is it?

The processor is fed with 3.3V and has VDDA connected to that voltage.

[InsignificantBit]

Yes, pretty much. There is nothing stopping you from supplying the Vref pin (or VDDA) with a voltage that's more precise than the internal reference, but if you don't need the precision, you can basically compare the measured values to the the internal reference.